Info Center

All Things Hip - The Ball and Socket Joint

Problems, Treatment, Surgery, Replacement

It is estimated that there are more than 300,000 total hip arthroplasties — hip replacements — performed in the United States every year. One of the most successful orthopedic procedures, it is also one of the most successful surgical procedures of any type performed today. Hip replacements can relieve pain, restore function and improve one’s quality of life. More than 90 percent of total arthroplasties work successfully and patients are generally pain free without complications for 10 to15 years postoperatively.

Dr. Shaver: When surveys are done, patient satisfaction following hip procedures is extremely high. In a recent publication it was noted that of 1.4 million Medicare patients undergoing hip replacement, 30-day mortality was only 0.4 percent. Indeed, the procedure affords our patients with great benefit performed at low risk. Let’s begin with the basics: what kind of joint is the hip and are there any other joints in the body like it?

Dr. Weisstein: The hip joint is essentially a ball and socket joint. In the human body there are other joints that are somewhat similar, like the glenohumeral (shoulder) joint. While they are both ball and socket type joints, the hip joint is distinct in that it bears the weight of the body. Obviously being bipedal human beings, we rely on our hips for weight-bearing whereas the ball and socket shoulder joint doesn’t bear much weight at all.

Dr. Shaver: What causes the hip to wear out?

Dr. Gore: Time, age, and wear and tear contribute to the hip wearing out. Weight can certainly be a factor. There are also inherent diseases, rheumatoid arthritis being one of the more common ones, but generally, the cause is wear and tear. Often times you will see people who have dysplastic hips — congenital or developmental deformation or misalignment of the hip joint — that aren’t perfectly formed and aren’t seated deeply enough.

“When a patient experiences hip pain and comes to you, is there something about the presentation that says it’s a hip, and is there something that says it probably isn’t hip?” — Philip Shaver, MD

Dr. Shaver: People with congenital hip problems, meaning it is present at birth, often do pretty well for a while and then eventually need treatment later in life.

Dr. Gore: Exactly. They’ll come in at younger age, depending on how severe the deformity is.

Dr. Weisstein: I’ll add to what Rufus said about causes. Certainly, I completely agree with the wear and tear, but something we’re seeing more commonly in the United States and with which we are all too familiar, is obesity as a risk factor for development of arthritis. Everyone has an ideal body weight and in orthopedic surgery and most surgical subspecialties in internal medicine, when we talk about body mass index, and obesity, we know that obesity most likely puts an undue stress on the joint. This can lead to early wear and tear, and early loss of cartilage.

Dr. Shaver: Let’s talk about the ball and socket. The ball is the head of the femur and the socket actually sits in the pelvic bones, right? As you’ve said, it articulates within this cup. Isn’t the vast majority of the hip surgery we do in adults due to osteoarthritis?

Dr. Diltz: I would say yes, but during the last 10 to15 years we are recognizing soft tissue problems earlier, even in collegiate athletes, and often in professional athletes. Alex Rodriguez, the New York Yankee’s third baseman, had two hip surgeries for impingement and injuries to the soft tissue. There are many famous professional athletes who place their hips in super physiologic positions that can cause damage along the edge of the hip. I believe that the vast majority of hip pain, particularly in 60- and 70-year-olds, is not an impingement problem and doesn’t need to be treated with arthroscopy. However, in the younger patient population, there are a significant number of people who have problems with the soft tissue above the hip.

Dr. Shaver: I imagine that the average patient you’re seeing is probably in their 70s.

Dr. Diltz: Yes. For patients in their 60s and 70s, I don’t think that hip arthroscopy is a viable option. Once the hips are worn out, you’re usually looking at a hip replacement. I don’t want to give people a false sense of hope that they can do a minor procedure once they have arthritis in the hip. The majority of our patients with arthritis need a total hip replacement.

Dr. Shaver: What exactly is wearing out? John, is it the cartilage on the articulating surfaces?

The most common patient seen needing a hip replacement has degenerative arthritis, which is wear and tear arthritis, followed by avascular necrosis or rheumatoid arthritis.” — John DeSantis, DO

Dr. DeSantis: The cartilage wears out, both on the acetabular side and on the femoral side. This results in bone-to-bone contact between the acetabulum (socket) and femoral head (ball). You can also get pathology [disease] just on the ball side, from a process called avascular necrosis [a pathologic process that results from interruption of blood supply to the bone], but the socket is normal. Avascular necrosis is actually very painful, usually more intense pain than the average degenerative arthritis patient. The most common patient seen needing a hip replacement has degenerative arthritis, which is wear and tear arthritis, followed by avascular necrosis or rheumatoid arthritis.

Dr. Shaver: Avascular necrosis means the blood supply is cut off, usually in the head of the femur, at the ball, if you will. Do you see that as part of an arthritic process?

Dr. DeSantis: There’s something metabolic or vascular going on. The bone in the head dies and then the cartilage collapses, which results in severe pain and loss of normal function.

Dr. Shaver: Would this present differently than someone with arthritis?

Dr. DeSantis: Usually there’s more intense pain and typically a more sudden onset than degenerative or rheumatoid arthritis.

Dr. Weisstein: Typically the patient populations that are presenting with avascular necrosis have either a history of heavy prednisone usage or steroid usage in the past, either for asthma or other potential rheumatologic problems. We often see it in patients who are alcoholics or recovering alcoholics. We see it here in the desert in our HIV population, and it’s thought that the antiretroviral drugs alter the circulation of fats within the body. And the hip, as Dr. DeSantis explained, is very sensitive to changes in circulation. The vasculature or the vessels in the femoral head are very fine and there can be sludging or slowing down of these lipids that are formed as a result of the antiretroviral drugs in the HIV population, so we see a lot of that here.

Dr. Shaver: Let’s talk about other causes of hip pain. When a patient experiences hip pain and comes to you, is there something about the presentation that says it’s a hip, and is there something that says it probably isn’t hip? Isn’t most hip pain actually anterior groin?

“My advice to patients at risk for falls is no small pets, no small children and no small rugs.” — Rufus Gore, MD

Dr. Gore: That’s the classic presentation. But five to 10 percent of patients complain of pure buttock pain while others have the classic groin pain. When a patient walks into my office and tells me they have hip pain, the first thing I do is to ask them where their hip is. If you ask 30 patients where their hip is, you’ll get 30 different answers.

Dr. Shaver: So, a patient is referred to you as anterior hip or groin pain, and when you talk to them, they give you their history — what do you do next? What is there about the physical exam, from watching them walk to examining them, that is a tip-off?

Dr. DeSantis: The patient will typically lose internal and external range of motion. I have the patient sit on an exam table or a chair and then just rotate their hip and see if they have restriction and if it hurts when this is done. They also tend to lose abduction — lifting their leg to the side. Usually if it’s arthritis, you can tell on the X-ray. If it’s not as obvious, we will get an MRI, and sometimes if the X-ray looks good, the MRI will show that they have a torn labrum, or sometimes they will have more subtle changes of arthritis where they have worn through the cartilage, but it’s not bad enough that the X-ray is showing it yet.

Dr. Shaver: For our readers, the labrum is what exactly?

Dr. DeSantis: It’s a ring of cartilage around the outside or around the border of the hip, on the socket side.

Dr. Shaver: When you watch someone walk, is there anything typical about their walk that tips off an arthritic hip?

Dr. DeSantis: Typically they thrust their rear end out to the side or to the back. And they walk with a stiff leg. Dr. Shaver: One thing that’s interesting to me is having patients with hip pain do straight leg raises, which generally is painful if you add resistance to their leg raises. But if you passively raise their leg and they have pain, it often suggests to me it may be something else, something sacroiliac or even neuropathic coming from lower back disease.

Dr. Diltz: When they’re actively raising their leg, that hip flexor muscle (the iliopsoas) often crosses right over the top of the articular hip, so when you provocatively test that, it will reproduce the groin pain. When they’re actively firing that muscle, it’s pushing that bursa down on the hip joint. We see that a lot with some of the different injuries in the hip. Often, it was written off as just a hip flexor injury, but it’s actually more of an articular problem with the head joint.

Dr. Shaver: Even with all our imaging tools now, I think you mentioned that X-ray is still really critical. Do you sometimes operate without anything more than X-ray?

Dr. Diltz: Yes, definitely. The majority of the time it should be.

“One of the questions that we get from patients is why their friend who had a hip replacement is out playing tennis, but they are not. I tell them that no two patients are identical.” — Jason Weisstein, MD

Dr. Weisstein: We rarely get an MRI unless we suspect soft tissue problems like a labral tear or potentially intractable bursitis or if we have X-rays that look normal, but can’t really put our finger on it, and maybe there’s a risk factor for osteonecrosis or avascular necrosis. Especially in our elderly population with hip pain, some of them will develop stress fractures, ones that have a fairly occult presentation. All orthopedic surgeons would agree that an X-ray should be the first diagnostic tool, both in the hip and the knee.

Dr. DeSantis: I will get an MRI of someone’s back if they’re saying their pain is going below their knee. Typically, hip pain stops at the knee. If it goes past the knee, then it’s a nerve problem from the answers back, and so we’ll order an MRI on the back because someone can have a bad hip and a bad back, as well.

Dr. Shaver: I think everyone here would agree that most surgeons say the best surgery is no surgery. So, what can we do nonsurgically? What can you do for a patient who comes in and is perhaps not the best candidate for surgery?

Dr. Weisstein: I think that lifestyle modification — learning how to do appropriate exercises that are low impact, like swimming, biking, tread mill, and elliptical, tend to be pretty tolerable for patients with hip arthritis. There’s obviously a litany of medications, but they fall under some broad categories, either nonsteroidal antiinflammatory drugs or acetaminophen.

Dr. Gore: Before you get into injections or prescription medications, patients can benefit from simple things: modification of activity, weight loss, stretching and strengthening. It’s also popular to do Tai Chi, yoga and things like that. Cane use can also be helpful.

Dr. Shaver: What about indications for surgery? I would think that the chief indication would be pain and decreased quality of life. Does the patient usually know when they need the surgery?

Dr. DeSantis: I think all patients are different. There are some patients that tolerate a great deal of pain and they will say they’re not ready for surgery. They come in for information. And you might see them back in six years or two years. And then there are other patients who start to have pain, an X-ray shows some arthritis and they tell me they want to be active and don’t want to cut back on walking or biking or things like golfing. They are more prone to get something done. So it’s really variable.

Dr. Shaver: Let’s say they want to go back to everything they ever did like jogging, running marathons and lifting weights. Do you say, “Those days are over — here’s a list of things you can do and here are some things you can’t do anymore?”

Dr. Weisstein: One of the questions that we get from patients is why their friend who had a hip replacement is out playing tennis, but they are not. I tell them that no two patients are identical. Their risk factors and past medical histories are different, their weight may be different and their motivation may be different. Their reaction to pain or surgical discomfort may be different. Expecting an outcome identical to that of a friend is probably not a realistic way of going into an orthopedic surgery visit when you’re thinking about a hip replacement.

Dr. DeSantis: I tell my patients that anything they do that has impact is going to have the potential for damaging or shortening the lifespan of the new joint. Around here, tennis is big. I would rather have someone play golf than tennis, but there are people who play tennis on their new knees and their new hips. I think those activities are putting them at greater risk for the replacements not lasting as long as they could.

Dr. Weisstein: We haven’t mentioned osteotomy [reshaping bone] in young patients with arthritis. Osteotomy is a way of realigning the relationship between the bones that form a joint. In our case, hip osteotomy realigns the relationship between the ball and socket. In younger patients in their 20s, 30s and even 40s, an osteotomy might be a better option than a joint replacement. Because, no matter how good our hip replacement technology is, there is still the unanswered question of why younger patients don’t do as well with joint replacements. The highest risk of failure is in males, age 40 to 55, and it’s probably because the requirements for males in this age range may exceed the capacity of what modern day hip replacements are actually able to offer. Dr. Shaver: Do you think it’s their activity and the amount of weight-bearing?

Dr. Weisstein: Activity level.

Dr. Shaver: Once you’ve done a hip replacement, is there a yearly follow-up?

Dr. DeSantis: I think everybody has different protocols. I will see patients every so many months the first year, and then if they’re having no symptoms, I may see them in a year or two. If it’s been several years and they’re not having trouble, I might have them come in every two or three years and get an X-ray.

Dr. Shaver: How does the patient know his hip is loosening or it’s time for the two-year visit? Dr. Weisstein : Like Dr. DeSantis pointed out, we like to detect problems early. If the replacement has become excessively worn, they will typically have symptoms of pain that may have led them to present in the first place with their arthritis, so they’ll have that same type of groin pain. I like my patients to follow up every year for the first two years and then every two years after that unless there is a new problem.

Dr. Shaver: Is there anything you see on the exam that says the hip is loosening or failing?

Dr. DeSantis: If it’s badly worn, the hip will sometimes slip out of place. The ball will come out of the socket. Unfortunately, we have a lot of patients who, despite being asked to come in every couple years, are feeling well and they don’t come in for eight years. And then in eight years, they’re having a problem and their polyethylene is completely worn and/or the hip is coming out of place.

“For patients in their 60s and 70s, I don’t think that hip arthroscopy is a viable option. Once the hips are worn out, you’re usually looking at a hip replacement.” — Matthew Diltz, MD

Dr. Diltz: Or people move and they lose follow-up with their doctor.

Dr. Shaver: When they come in and the hip is worn out, what do you do? Is it a minor procedure?

Dr. Weisstein: You can have it on either side. It can affect the ball side, meaning the femur, or it can affect the socket side as part of the pelvis and it could be as minor a situation as we just want to observe it with serial X-rays or maybe do a liner exchange — or we pop out the plastic and put in a new piece of plastic. The problem is, sometimes we may not be able to match the parts. Many patients don’t remember where they had their surgery and it’s sometimes difficult to identify the parts. Sometimes we have to do major bone work because it’s not just the plastic that’s wearing out. The plastic can incite a lysosomal [enzyme] reaction, actually dissolving bone and cause osteolysis [an inflammatory process that can result in bone loss] and that becomes a very complicated situation, where sometimes we have to review entire components or cut through the bone to get the components out.

Dr. Shaver: How big a procedure is this compared to the original operation? Is it just the same?

Dr. Gore: Most of the time it’s bigger. I don’t think any surgery on the hip is ever minor, but there are major surgeries and drastic surgeries, such as the osteolysis that Jason was mentioning and you have bone that’s been destroyed or reabsorbed.

Dr. Weisstein: It’s not uncommon to take the plastic out and the cup actually breaks. No revision is considered easy.

Dr. Shaver: It’s estimated that there are 310,000 individuals in the United States with hip fractures. Osteoporosis is one of the problems and often it’s just a simple fall. The lifetime risk of hip fracture is 17.5 percent for women and 6 percent for men. The estimated cost in the United States is between 10.3 and 15.2 billion dollars. This is really a major, major deal.

Dr. Diltz: Sometimes people fall and break their hip, and sometimes they break their hip and then fall. Some of it has to do with the bone and stability of the structural support because of bone loss in that area.

Dr. Gore: My advice to patients at risk for falls is no small pets, no small children and no small rugs. Dr. Shaver: I wonder if we communicate well. For instance, are we asking our patients who fall and end up in the hospital how they fell? Are we checking for osteoporosis? And by the way, are we asking patients to look in their homes for things like throw rugs. How can we help prevent our patients from falling in the future?

Dr. Diltz: I think a lot of internists are proactive with their patients. Whether it’s just a radius fracture with a partial fracture of the spine, or a hip fracture, it should trigger a series of tests that can look at the bone density. There’s a specific bone density study that we can look at, and I think that those three types of fractures should trigger that. The falling is a separate issue, whether it’s a syncopal event, or a medical cause. Eisenhower is good with mechanical falls. Patients can be referred to Eisenhower’s Balance Institute.

Dr. Shaver: The Balance Institute is a great idea. We just need to make sure we communicate this with the patient’s primary care doctor for follow-up.

Dr. Diltz: The way that information is gathered within medicine is changing and there’s a lot of incentive to really focus on the electronic records, to increase communication and develop more protocols. Eisenhower has a geriatric program under the direction of Dr. Sheda Heidarian. One of her big focuses has been associated with delirium and dementia and being aware of that. Dr. Weisstein : In closing, I’d like to say that one of the unique things about Eisenhower Desert Orthopedic Center compared to other orthopedic groups here in the Coachella Valley, is that we really offer the full spectrum of treatments for hip disease from pediatric orthopedic specialists to soft tissue specialists like Dr. Diltz, who performs the largest volume of hip arthroscopy in the valley, to joint replacement specialists like myself, Dr. DeSantis and Dr. Gore.